The size of the image of an object, which is at infinity, as formed by a convex lens of focal length $$30 \mathrm{~cm}$$ is $$2 \mathrm{~cm}$$. If a concave lens of focal length $$20 \mathrm{~cm}$$ is placed between the convex lens and the image at a distance of $$26 \mathrm{~cm}$$ from the lens, the new size of the image is
A slit of width $$a$$ is illuminated by red light of wavelength $$6500 \mathop A\limits^o$$. If the first diffraction minimum falls at $$30^{\circ}$$, then the value of $$a$$ is
Which of the following statements are correct with reference to single slit diffraction pattern?
(I) Fringes are of unequal width.
(II) Fringes are of equal width.
(III) Light energy is conserved.
(IV) Intensities of all bright fringes are equal.
In the Young's double slit experiment a monochromatic source of wavelength $$\lambda$$ is used. The intensity of light passing through each slit is $$I_0$$. The intensity of light reaching the screen $$S_C$$ at a point $$P$$, a distance $$x$$ from $$O$$ is given by (Take, $$d<< D$$)